Machines for packaging a variety of products are used at various production sites. To maintain the quality of a variety of products (packaging targets), such packaging machines may need appropriate sealing. Techniques have been developed to evaluate sealing achieved by a packaging machine or to detect a foreign object bitten in the sealing.
Japanese Unexamined Patent Application Publication No. 2007-302261 (Patent Literature 1) describes an automatic packaging machine including a sealing mechanism that is driven by a servo motor. This automatic packaging machine compares a threshold with initially recorded reference operational data to evaluate sealing achieved by the sealing mechanism. The automatic packaging machine changes the threshold when resuming a packaging process that has been stopped.
Japanese Unexamined Patent Application Publication No. 2008-037450 (Patent Literature 2) describes an object detector included in a packaging machine. The packaging machine inserts products into a tubular film that is fed, and seals the center and the two ends of each film portion to complete individual packages. The object detector can detect an object bitten at a sealant in an end sealing mechanism of the packaging machine.
Japanese Unexamined Patent Application Publication No. 2010-006474 (Patent Literature 3) describes a packaging machine and a motor controller that are capable of detecting an object bitten in a packaging film without using sensors for object detection. Under constant disturbance surrounding the shaft of an end sealer, the packaging machine and the motor controller can detect disturbance with a smaller amplitude than the constant disturbance or can detect disturbance having delayed changes in the amplitude cycles. The packaging machine and the motor controller can achieve lower cost and smaller size, and higher reliability.